Decided to go back to this today and try to sub 5. I ended up getting this within 15 minutes! I did not expect this one to be it- I had a very sloppy early game and threw away easy time in 8-1 as well. Great 8-2 and 8-4 got me this though! I'm definitely going to get a 4:58 and maybe even a 4:57.
I'll be running this at SGDQ as a bonus incentive after a 4 way warpless race. Check this schedule to see your local time for when this run will be! https://gamesdonequick.com/schedule
-- Watch live at https://www.twitch.tv/kosmic

You can access glitchy worlds (similar to the minus world) by swapping between Famicom SMB and Tennis cartridges without powering the game off. This works because without powering off, the RAM values are never cleared between these games. When you hold A+Start in SMB1 it takes you back to the world you last played. Tennis must use this RAM address for something, so when you swap back to SMB1 you're taken to whatever numbered world that Tennis stuck in that address. This doesn't work on the Toaster NES but it does work on a top loader NES. -- Watch live at https://www.twitch.tv/kosmic

EDIT: Turns out the time is 4:59.873. It was timed 6 frames too slow the first time around.
The first sub 5 completion of All Stars SMB1! When I started playing this version I just wanted to beat the previous record (5:01.70 by Andrewg1990), but after beating it with a time of 5:01.370 I realized I could just BARELY get sub 5 if I put together the run I wanted. So that's what I did! 2 frames slower in 8-4 and I would not have gotten sub 5. It's no secret that I'm not a huge fan of this version of the game, but I'm very proud of this run!
Here's my commentary about this run which explains the strategies I needed to do to get this time, and the differences between this version and the NES version: https://youtu.be/uiXr-wryGzQ
I'll be playing the warpless category of this game now. Watch live at https://www.twitch.tv/kosmic

Got the first 4:55 and the first 5:03 glitchless a week apart, both probably the final resting place for each category in terms of the seconds digit.
I wasn't playing well today so I did a few glitchless attempts and got this. Not playing well ➡ Play glitchless ➡ Get WR within 20 minutes. If that doesn't speak volumes about glitches vs. glitchless in speedruns I don't know what does. But yeah everyone knows glitches are cheating and take no skill.
Watch live at https://www.twitch.tv/kosmic

New world record! First time I've held the warpless record since November 2012. Basically pulled off everything I was going for perfectly. There's still time to save by going for some more time saves though! 18:59 some day!
I basically played exactly the same as the record until 7-4 where I had a faster bowser kill and came out 0.35 ahead. Andrewg lost over a second in 8-4 in the previous world record, so that's where the rest of the time save came from. -- Watch live at https://www.twitch.tv/kosmic

World record as of 5/20/2018. Another one for the books :) this turned out to be a bit harder than I thought but this run is pretty clean and I'm happy with it. The previous world record was 19:58 by Goofychocobo.
The all stars version is a port of smb1 that has slight differences, but these slight differences make a big difference in the speedrun. Mario bounces slightly higher off enemies, there are more enemies (the NES despawns many enemies to reduce lag), the enemies have more accurate (which usually means bigger) hitboxes, podoboos jump higher, some enemies like hammer bros. give different patterns, and the physics for breaking blocks are different.
Small differences like how high you bounce off of an enemy, an enemy spawning where one wasn't on NES, and how high podoboos jump really mess you up when you have built up so much muscle memory in the NES version. Eventually I got used to all the things All Stars was throwing at me and pulled this run together :)
Obvious improvements include: Faster 4-4 bowser kill, getting a good firebar pattern in 6-4, navigating 7-4 properly, doing 8-2 stairs properly, and having a cleaner 8-4. There are more improvements outside of these, but these alone add up to about 5 seconds of time save. In other words this run is still quite improvable!
I'll be doing Minus World Ending speedruns now.
Watch live almost every day at https://www.twitch.tv/kosmic

Previous world record was 5:06.99 set by andrewg ~5 years ago. This only took about 15 minutes of doing attempts- shows how far we've come in 5 years! And how silly people are when they say runs that use glitches take no skill.
Watch live at https://www.twitch.tv/kosmic